The practice of taking a new name has its origin in the early Christian practice of the newly baptized disassociating themselves from their pagan identities and invoking the aid of a saint or martyr by taking his or her name.

This practice was reflected in the life of members of Religious orders and communities over the centuries and in the taking of a saint's name at confirmation.

It is commonly held that the custom began with Pope Sergius IV, elected in 1009. Tradition holds his original name was Peter.

Had he kept his name, he would have become Peter II. He thought it unseemly that he should be of the same stature as the original Peter, so he changed his name out of deference.